One who builds, how much must he build to be liable? One who builds any amount; one who chisels [a stone], strikes with a hammer or with an adz, [or] drills, any amount, is liable. This is the rule: Anyone who works, and his work endures, on the Sabbath is liable. Rabban Shimon ben Gamliel says; Also one who strikes with a sledge hammer on the anvil while working is liable, since he is as one who improves the work.